Apparatus and method for increasing spin relaxation times for alkali atoms in alkali vapor cells

Abstract

An atomic vapor cell apparatus and method for obtaining spin polarized vapor of alkali atoms with relaxation times in excess of one minute is provided. The interior wall of the vapor cell is coated with an alkene-based material. The preferred coatings are alkenes ranging from C18 to C30 and C20-C24 are particularly preferred. These alkene coating materials, can support approximately 1,000,000 alkali-wall collisions before depolarizing an alkali atom, an improvement by roughly a factor of 100 over traditional alkane-based coatings. Further, the method involves a combination of one or more of the following: the use of a locking device to isolate the atoms in the volume of the vapor cell from the sidearm used as a reservoir for the alkali metal vapor source, careful management of magnetic-field gradients, and the use of the spin-exchange-relaxation-free (SERF) technique for suppressing spin-exchange relaxation.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. provisional patent application Ser. No. 61 / 409,004 filed on Nov. 1, 2010, which is incorporated herein by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with Government support under Grant No. N00014-05-1-0406 awarded by the Office of Naval Research, and under Grant No. PHY-0855552 awarded by the National Science Foundation. The Government has certain rights in this invention.INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC[0003]Not ApplicableBACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The present invention pertains generally to atomic vapor cells, and more particularly to method for achieving extremely long-lived polarization in alkali vapor cells with walls coated with long chain alkenes.[0006]2. Description of Related Art[0007]Long-lived ground-state coherences in atomic vapor cells fo...

AI Technical Summary

Benefits of technology

[0019]Polarization lifetimes of atomic populations and coherences in excess of 60 seconds in alkali vapor cells with inner walls coated with an alkene material are illustrated. Long relaxation times of spin polarized vapor of alkali atoms can be achieved with atomic vapor cells that have a bulb with inner walls that have been coated with an alkene-based material. The “anti-relaxation” materials of the invention can support approximately 1,000,000 alkali-wall collisions before depolarizing an alkali atom, an improvement by roughly a factor of 100 over traditional alkane-based coatings. Relaxation times are also lengthened by using a combination of one or more of the following: the use of a locking device to isolate the atoms in the volume of the vapor cell from the sidearm used as a reservoir for the alkali metal, careful management of magnetic-filed gradients, and the appropriate use of the spin-exchange-relaxation-free (SERF) techniques for suppressing spin-exchange relaxation.

[0023]According to one aspect of the invention, a method for reducing the relaxation rate of polarized vapor atoms is provided that decreases relaxation due to atom-wall interactions, atom-atom interactions and atom-vapor source interactions.

[0024]Another aspect of the invention is to provide an atomic vapor cell wall coating that will preserve atomic spin polarization even after many impacts with the coating.

[0025]Another aspect of the invention is to provide an atomic vapor cell that isolates the vapor from the source of vapor and improving the rate of relaxation of the polarized atoms.

Problems solved by technology

The sensitivity of atomic vapor cell devices is generally limited by the number of atoms and their spin coherence lifetime.

While diffusion limited relaxation times of a few seconds can be achieved by this method, it also incurs additional relaxation via alkali-buffer gas spin-destruction collisions.

Furthermore, the additional buffer gas can produce undesirable broadening of optical transitions.

However, this is the upper limit for paraffin.

However, the performance of paraffin coatings quickly degrades at temperatures above 60-80° C. and it may not be available as a coating in some settings.

In addition, paraffin does not survive the elevated temperatures required by the anodic bonding process used in the production of microfabricated vapor cells.

In particular, a multilayer coating of octadecyltrichlorosilane [OTS, CH3(CH2)17SiCl3] has been observed to allow from hundreds up to 2100 bounces with the cell walls and can operate in the presence of potassium and rubidium vapor up to about 170° C. However, the quality of such coatings with respect to preserving alkali polarization is highly variable, even between cells coated in the same batch, and remains significantly worse than that achievable with paraffin.

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